The present invention relates, in general, to the field of thin-film devices and techniques for manufacturing the same. More particularly, the present invention relates to a castellation technique for improved lift-off of photoresist in thin-film device processing of particular utility in the production of magnetic data transducers and recording heads.
Current thin-film disk and tape head structures require the formation of insulation layers to improve the electrical isolation between various conductive layers in the structure. A particular head and conductor isolation structure is disclosed in U.S. Pat. No. 5,850,324 issued Dec. 15, 1998 for; xe2x80x9cMagnetoresistive Head Having Electrically Isolated Conductor Leadsxe2x80x9d. Patterning of the insulating layers is achieved by what is commonly known as the xe2x80x9clift-offxe2x80x9d process. A particular photoresist lift-off technique and a discussion of other prior art techniques is disclosed in U.S. Pat. No. 5,658,469 issued Aug. 19, 1997 for: xe2x80x9cMethod for Forming a Re-Entrant Photoresist Lift-Off Profile for Thin Film Device Processing and a Thin Film Device Made Therebyxe2x80x9d. The disclosures of the aforementioned patents are herein specifically incorporated by this reference.
Conventional lift-off structures have been, by their very nature, primarily limited to the lift-off of relatively thin films only. However, and particularly with respect to magnetic tape heads having thicker permanent magnet (xe2x80x9cPMxe2x80x9d) stack designs, increased thickness insulation layers are required to cover the increased residual re-deposition of materials produced by increased ion-milling operations as well as to provide planarization of the resultant structures to depths of up to three to five times that encountered in conventional disk drive heads.
Further, as tape heads move towards an ever increasing number of channels on a single head, extra thick insulating films are needed for acceptable electrical yield of each of the channels in order to ensure high yields for the head as a whole.
Disclosed herein is a castellation technique for improved lift-off of deposited thin films on photoresist in thin-film device processing of particular utility in the production of magnetic data transducers and recording heads. By correctly designing the edge boundary of a photoresist structure, enhanced regions of low resist edge bombardment and low deposit penetration may be achieved. These enhanced regions enable the lift-off of extra thick insulation regions that would not be otherwise achievable through the use of conventional techniques with and without castellation.
Specifically disclosed is an improved method for lifting off extra thick insulation layers with patterned photoresist through the optimization of the photoresist edge design in order to achieve improved electrical isolation characteristics.
Particularly disclosed herein is a thin-film device produced by a process comprising the steps of patterning a photoresist layer overlying a thin-film device structure formed on a substrate. The photoresist layer includes a plurality of peripherally extending tabs having interstitial spaces therebetween with at least one of the plurality of tabs having a lateral width greater than a corresponding lateral width of adjacent ones of the interstitial spaces with the width of the interstitial spaces being substantially on the order of the photoresist thickness. The photoresist layer and the substrate are overlaid with a deposited layer and the photoresist layer and the deposited layer overlying the photoresist layer are thereafter removed to expose the thin-film device structure.
Still further disclosed herein is a photoresist lift-off structure for forming a thin-film device. The structure comprises a photoresist layer overlying a thin-film device structure formed on a substrate. The photoresist layer includes a plurality of peripherally extending tabs having interstitial spaces therebetween with at least one of the plurality of tabs having a lateral width greater than a corresponding lateral width of adjacent ones of the interstitial spaces.